Sometimes we get a call or an e-mail from a frustrated customer: “I have a brand-new set of your tires, and both wobble when I mount them on my rims.” In most cases, it is not the tires’ fault. Usually the problem stems from the difficulty of mounting tires on poorly designed rims. However, there are some tricks for mounting tires on these rims.

Above, you see a correctly mounted tire. Most tires made today have a line molded into the sidewall (arrows). This line must be visible all around the tire, and parallel to the rim edge. The line not only helps seat the tire, it also serves as a visual indicator that the tire is concentric with the rim. (Usually, the line is a little higher above the rim, but always parallel to the rim edge.)

Above are three 700C rims, which all have the same outer diameter. However, the cross sections show that they are very different on the inside. Rim 1 is a proven design. Rim 2 has a shallower well (the place where the tire mounts). Rim 3 has a very deep well. Tires seat differently on each of these rims.

When you mount a tire, the tire beads need to go over the rim’s hook (above; the foam is used to hold the tire in shape). Tire beads are what holds the tire on the rim. They don’t stretch much – otherwise, the tire would just blow off the rim when you inflate it.The well of the rim has a curved bed. When you mount the tire, the tire beads drop into the center of the rim’s well bed. This provides enough slack to get the last bit of tire bead over the rim’s hook on the opposite side. As you inflate the tire, the beads slide up the rim’s curved well bed until they seat tightly underneath the rim’s hooks.

The photo above shows Rim 1. The tire’s beads fit perfectly onto the well bed and underneath the hook. The tire will seat concentrically by itself as you inflate it. The bead seat diameter is 622 mm, as industry standards specify (ETRTO). This is how rims should work.

Rim 2 has a shallower well. The bead seat diameter is 624 mm, which makes the well bed higher than the standard 622mm. To seat correctly, the tire has to stretch by 2 mm in diameter. This translates into 6.5 mm (1/4″) along the tire’s inner circumference, which is a lot of stretch for a tire bead. Often, the beads don’t stretch enough, and don’t quite reach the rim walls (arrow). Then the tire will wobble on the rim. Putting talc (baby powder) on the tire bead may help it slide into position. A very thin and slippery rim tape also can be helpful.

The high well bed also makes the tire difficult to remove: It is difficult to insert a tire lever underneath the tire bead, because it is stretched so tight onto the rim.

Rim 3 has a very deep well. The tire is not supported by the well bed at all (arrows). The tire has to float. When you inflate this tire, it cannot just slide into position on the well bed. You will have to manipulate the tire until it is seated correctly.

Unfortunately, several common rims for wider tires, including the Velocity Synergy, several Velo-Orange models, and the no-longer-available Grand Bois, have overly deep wells. This makes mounting tires difficult. The sole advantage is that the tires come off the rim easily.

On their 650B rims, Synergy tried to “fix” the problem of poorly seating tires by increasing the overall rim diameter. In my experience, this has made things worse, because now the hook is in the wrong place. There is nothing to locate the tire: The well still is too deep, so the tire cannot sit on the well bed. And the hook is too high, so the tire cannot sit underneath the hook.

If you have rims with wells that are too deep on your bike, there are some tricks for mounting tires on them. There even is a “fix” that can overcome the problem of the overly deep wells to a large degree.

On all rims, even well-designed ones, tires often don’t seat well at the valve. The tube is reinforced here, making it stiffer, and it sometimes gets caught under the tire bead. Above, you see how the molded-in line moves away from the rim at the valve. (Often, this is more pronounced.) Not only will this cause the tire to wobble, but if the tube is trapped under the beat, it can chafe until you get a flat tire.

With the tube barely inflated (~5 psi), push the valve stem inward as far as you can. This usually frees the part of the inner tube that is trapped.

Harder to fix is the problem shown above: The line that is molded into the tire sidewall disappears into the rim (arrow). This often happens on rims where the wells are too deep, such as the Synergy Velocity shown here. (The Grand Bois rims we used to sell unfortunately were not much better.) It also can happen if the well is too shallow, and the tire bead does not contact the rim sidewall.

Push the tire to get it into the right place. Inflate it to about 15 psi, and use both hands to push it away from you, until the molded line appears. Go around the tire on both sides until the molded line is visible everywhere and parallel to the rim edge. This takes patience. It can be frustrating, and it’s the last thing you want to do when you have a flat on the road, and all your friends are waiting for you to get back on the road.

To address the problem of the overly deep wells, you can add two layers of rim tape (or handlebar tape, which is the correct width for 23 mm-wide rims). This raises the bottom of the well. Now the tire should seat correctly without as much manipulation.

Do not ride a poorly seated tire! The tire could come off the rim and cause a crash.

Of course, it would be nice to have correctly designed rims, where the tires seat automatically as you inflate the tubes.

Update 3/19/2014: Grand Bois has redesigned their rims with a shallower well, so they fit the tires properly. The new rims are in stock.

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About Jan Heine, Editor, Bicycle Quarterly

I love cycling and bicycles, especially those that take us off the beaten path. I edit Bicycle Quarterly magazine, and occasionally write for other publications. One of our companies, Bicycle Quarterly Press publishes cycling books, while Compass Bicycles Ltd. makes and distributes high-quality bicycle components for real-world riders.

41 Responses to Mounting Tires on Rims with Deep Wells

I recently bought a pair of Hetre tires and installed them on my rims (they are neither of the two brands you mention with high sidewalls), and have the problem you describe with high-walled rims. I spent about a frustrating 1/2 hour on each wheel to correct the problem and could not get them to seat properly. I’m very handy with this sort of thing, and intuitively did what you just described, aside from doubling rim tape. I may have to try that.

Anyways, it just got me thinking, JPW shaves his Hetres, and he had mentioned in his article that the tire has to be seated perfectly before shaving begins. Do you know if he employs any other tricks?

Shu-sin,
No special tricks really, but I do use my “mounting station” for rims and tires that are difficult to seat.
Working at a comfortable height and having the wheel laying flat, especially if a soapy water solution is needed, helps make the whole process much easier.
Here is a link to show the “station” that was also pictured in BIcycle Quarterly Summer 2011 issue. http://www.flickr.com/photos/49353569@N00/7262839928/in/photostream

+1 on the use of a slippery substance for help in bead seating. Schwalbe’s Easy Fit and Rema’s Bead Butter have both given me good results. I expect a little Dawn in water would work just as well. It seems like bicycle tires are the only ones routinely installed dry.

great subject for discussion. what rim to choose for 650?, seems I’ll have to resort to fixes, would never have thought about well depth before. previous experience with Mavic G40, the LBS always placed several layers of reinforced packing tape in place of a rim strip, to protect the tube from the ferrules, but not for bead setting.

The new Pacenti rim seems promising – Peter Weigle has mentioned that the tires seat perfectly without doing anything special. They are very light, which means that they will wear out sooner, but I’d pick a rim that allows me to mount tires without hassle any day.

This post is extremely helpful and makes it very easy to understand the need for good rim design. The effort put into the pictures is evident and thoroughly illustrates the issues. Thank you so much for posting it. Looking forward to seeing how this information influences the products you sell. Do you have a measurement for the wall height of the grand bois 650b rims? Couldn’t find it on Compass Cycles site.

The deeper the well, the easier to mount the tire. On the other hand, the more you curve the bottom of the well, the weaker the rim profile gets.

From the above, it’s obvious that a wider rim can have a deeper well, and thus make it easier to mount the tire. The three rims in the photos have very different well depths, but two of them aren’t exactly ideal.

Great stuff. Thanks for this and for being willing to cut up expensive components to properly illustrate. So are you going to review the 650B Pacenti rims? And why on earth won’t Mavic make a 650B? Is it coming and we just don’t know it yet? Regardless, looking forward to your version. Can you give us some insight on ETA, etc? Thanks, Jan!

Mavic used to make 650B rims, starting in 1933 or so. (They were among the first to offer aluminum rims.) They stopped making them when there was little demand. When the Confrerie des 650 contacted them to see about a new 650B rim about 15 years ago, they said: “We just scrapped 800 or so 650B rims!” Since then, they haven’t been interested in 650B rims. Maybe that will change with the new 650B mountain bikes, but most mtb rims are disc specific and not very useful for our bikes.

Regarding Compass rims, we generally don’t comment on our future projects. It is too hard to predict how long it takes until something is ready for sale. We don’t want to rush development just to meet deadlines.

Thanks for a very informative and helpful post. I have had the exact same problem mounting Hetres on Synergy rims, and have had to use my hands to manually coerce the bead to seat properly (often resulting in callouses). I hadn’t thought about the extra layer of rim tape– nice tip!

When mounted correctly, all tires we sell are safe. One issue may be that the current 23-mm-wide rims are a bit narrow for the wide 650B tires. When you fit very wide tires on relatively narrow rims, seating them correctly may be harder.

Hi, Jan. Please forgive this comment that’s only somewhat related. I just saw this article:http://redkiteprayer.com/2012/05/specialized-roubaix-armadillo-elite-tire/
which said, “Of all the tires they tested, the tire with the lowest rolling resistance, i.e. the fastest, was …” the heavier, cushier one. I thought of you right away, and your comments about when the racers will start to see the light. :-)

Tire performance sometimes can be surprising. However, I don’t put much faith in those Finnish tests. They are still testing tires without a rider on the bike. Unfortunately, that means that a harsh-riding tire that doesn’t deflect much can post great results. Once you factor in the suspension losses in the rider’s body, things look quite different, though.

Good post. I have noticed this with Velocity Synergy rims and my usual Panaracer Pasela commuter tires. It hasn’t bothered me too much- I just try to roll the bead out with the tube partially inflated. It takes about 15 extra seconds. Personally I have more trouble with rim/tire combos that are a little too tight and wind up breaking tire levers and pinching tubes trying to get the tire on the rim.

Conrad,
For tight tire-rim combinations try Park’s TL-4 tire levers, they are great imo.
I’ve never broken one, they are broad at the tip but very thin. They can get under a tight bead easily and are strong enough to lever it over the rim. They don’t have hooks to catch a spoke but I haven’t found that to be a problem.

They have made tire changes easier, and I haven’t pinched any tubes since I started using them.
Highly recommended!!!

Regarding … “Do not ride a poorly seated tire! The tire could come off the rim and cause a crash.” … John S Allen just pointed me to an article by David Gordon Wilson in Human Power #51, pages 16-18. I think you will find it interesting.

Tubeless ready rims have a well formed hook to firmly grasp the Hetre’s bead, and shallow shelf that tends to guide the bead in place, the center channel is purposely deep however. The key to mounting a Hetre on this type of rim with defined hook is to pull the last bead section over with fingers, as there’s not enough room for a lever. UST (Universal System for Tubeless) rims appear to be a good match for Hetre’s bead as well; it’s only a matter of time before more of these become available for rim brakes in 650b.

FYI, the US manufactured tubeless ready A23 in 650b with rim brake sidewalls from Velocity is now shipping; an initial report states the Hetre bead fits snug and uniform. After experiencing the benefits of a much wider rim, I feel 23mm is limiting for the Hetre in overall performance, and more suited for the weight concerned user. I had Cypres tires mounted on 700c A23s, the bead fit very snug, and it was an OK match in most areas of performance, but would have preferred a wider rim with this tire also.

Jan, just to clarify, are you saying that tire bead height, depth and shape is generally a constant? I’m just wondering if there is something specific with the beads on some tires that may be more prone to seating issues with some rims, since I have set of Velocity Synergies that are mounted with Marathon Supreme tires, and have never had this problem. I have the same tires on Dyads and Rigida Andra 30 rims (between the three, there seems to be significant variance in the rim well height) and again, have never seen this problem with those tires.

are you saying that tire bead height, depth and shape is generally a constant?

Yes. The ETRTO norms are very specific on this. Unfortunately, it seems that many rim makers today don’t understand how a tire seats on the rim. (The Grand Bois rims show what happens if you leave the internal construction up to a rim maker!)

The difference between tires is not in the bead shape, but in how much they can flex and take up an irregular shape. Tires with super-stiff sidewalls, thick treads and wire beads, like your Schwalbe Marathons, hold their shape more easily. You can lean the tire by itself against a wall, and it will be round. A Grand Bois Hetre will collapse into a small heap. A stiff tire is easier to mount concentrically on a poorly designed rim. The downside of a stiff tire is a poor ride and high rolling resistance.

The more the tire sidewall can flex, the harder it is to seat the tire on a rim that does not support the tire well. This means that supple tires and wide tires are harder to seat. The Grand Bois Hetre combines both features. Add to that the relatively narrow rims (for a 41 mm tire) most of us are using, and you compound the problem. This doesn’t need to be so. On my Urban Bike, I have an old Mavic Module 4 rim on the rear wheel and a Wolber Super Champion on the front, and my Grand Bois Hetres seat on both rims at the first attempt with no finessing.

Wide tires with supple sidewalls add so much to the enjoyment of riding a bike that I am not willing to give them up, just so I can use poorly designed rims.

Just to clarify, the Marathon SUPREME is a relatively lightweight tire with a folding bead that is quite different from the various heavy versions of the Marathon. In 700 x 32, the Supremes weigh about 375 grams, vrs about 415 grams for the Hetres in 650 x 42. The sidewalls are what Schwalbe calls “liteskin,” i.e., relatively supple. I’ve found them faster, better handling, dramatically more durable and more comfortable to ride than, say, Conti Gatorskins.

Discovered The new Pacenti rim in 32 hole is already spoken for, sold-through. Slightly disappointing, as I was thinking 32 hole hubs/rims. I’ll be considering other brands from now on.
always in the past, my wheels have been 36 hole cross 3, or cross 4, just seems like modern trend is 32 hole.

The company that bought rims will be offering them for resale. You can contact sean@rawlandcycles.com today to reserve your set. We will have a follow up shipment landing shortly thereafter with LOTS of 32* rims.

Please remember that we will have plenty of 28* and 36* hole rims available through bikelugs.com in late June.